Field
Exemplary embodiments of the invention relate to a light emitting device, and more particularly, to a light emitting device configured to improve heat dissipation efficiency, electrical characteristics and mechanical stability.
Discussion of the Background
Recently, with an increasing demand for small high-output light emitting devices, the demand for large flip-chip type light emitting devices having good heat dissipation efficiency also is increasing. A flip-chip type light emitting device includes electrodes directly bonded to a secondary substrate and does not require a wire for supplying electric power to the flip-chip type light emitting device from an external power source and thus has much higher heat dissipation efficiency than a lateral type light emitting device. Thus, upon application of high density current, the flip-chip type light emitting device may effectively conduct heat towards the secondary substrate and may be suitably used as a high-output light emitting source.
In addition, to reduce the size and increase the output of a light emitting device, there is increasing demand for a chip scale package in which the light emitting device is used per se as a package by omitting packaging the light emitting device in a separate housing or the like. Particularly, since the electrodes of the flip-chip type light emitting device may provide a function similar to leads of the package, the flip-chip type light emitting device may be suitable as a chip scale package.
When such a chip scale package type device is used as a high-output light emitting device, a high density electric current is applied to the chip scale package. When a high density electric current is applied to the package, the amount of heat generated from the light emitting chip is increased in proportion to the electric current, so that the heat dissipation efficiency of the high-output light emitting device becomes a major factor in determining the reliability of the light emitting device. Therefore, there is a need for a high-output chip scale package that has high heat dissipation efficiency and good mechanical stability to ensure high reliability. Moreover, when the chip scale package is mounted on a board including a conductive circuit via an adhesive material such as solder, pastes, and the like, the adhesive material flows along the electrodes of the chip and the circuit of the board, thereby possibly disconnecting the electrodes and/or causing a short circuit between the electrodes. Therefore, there is a need for a structure having good mechanical and electrical stability so as to prevent short circuiting upon mounting.